Apparatus for building up laminate insulation and like structures



C. W. DAVIS AND W. S. BROWN.

m. w. DAVIS AND P. H. w.smm1, EXECUTORS or c. w. DAVIS, DEC'D. IAPPARATUS FOR BUILDING UP LAMINATE INSULATION AND LIKE STRUCTURES.

. APPLICATION FILED MAILZQ, I920. 1,420,91 1

3% m H m. m

, form; and paper UNITED STATESNRPATENT OFFICE.

DECEASED;

ECUTORS ASSIGNORS TO STANDARD -UNDERGROUND CABLE COMPANY OF PITTSBURGH,PENNSYLVANIA, A CORPORATION OF PENN SYLVANIA.

APPARATUS FOR BUILDING UP LAMINATE INSULATION AND LIKE STRUCTURES.

Specification of Letters Patent. Patented June 2'7, 1922.

Application filed March 29, 1920. Serial No. 369,638.

To all whom it may concern:

Be it known that we, CHARLES V. DAVIS, residing at Edgeworth, county ofAllegheny, and State of Pennsylvania, and V TILLTAM S. BROWN, residingat Pittsburgh, in the county of Allegheny and State of Pennsylvania,both citizens of the United States, have invented or discovered certainnew and useful Improvements in Apparatus for Building Up LaminateInsulation and like Structures, of whichimprovements the following is aspecification.

Our invention relates to machinery for wrapping sheet material insuperposed layers upon a central core or mandrel and for filling andintegrating the structure as it is built up, with a substance applied.in llquld form. The invention has a wider field of applicability, butwe have conceived and developed it in relation to the making ofelectrical cables and condensers. We shall describe it as embodied inmachinery for making cables, and in the sequel we shall indicate itsapplicability, first, to the making of electrical condensers, and thento the making of articles of like form regardless of the kind of serviceto which they are put.

In making electric cables, it is common to envelop a conductor in a bodyof insulation built upon it and consisting of layers of paper soakedfull of and integrated with a substance called insulating compound. Thepaper is applied in the form ofa ribbon or tape, the successive layersbeing wrapped on helically; the insulating compound is a petroleumderivative, or an equivalent substance, and is applied in liquid andcompound are brought together and built upon the conductorsimultaneously, in a single 0 eration.

A difficulty incident o the wrapping-on of the paper lies in the factthat air-bubbles are often wrapped within the turns of the strip. An airbubble so caught and incorporated in the insulation is a point of weak--ness and becomes a of insulation, when loaded to the'limit of itscapacity.

Our invention is directed to the-prevention of such bubble entrapping.-

In the accompanying drawings Figs. 1 and point of breaking down '2'showin vertical-section alternate forms of the cable in service is a machineof our invention. Fig. 3 is a view in transverse section on the planeindicated by the line III-III, Fig. 1. The usual apparatus includesmeans for causing the unfinished cable to advance in axial line, a reelof tape describing planetary motion around the cable, its axis soinclined that the pull of the advancing cable will unwind the tape fromthe reel and lay it down upon the cable in the desired helicalformation; and, in addition to or in association with theseinstrumentalities, means are provided for pouring insulating compound incontinuous stream upon the point where the tape is being progressivelywrapped upon the cable. The difficulty already defined is consequentupon this: that, while during half the planetary turn of the reel thevery point, where the tape meets the surface of the cable, is exposed tothe stream of insulating compound,'during the other half of the turn,the advancing strip of tape shields that point from direct access of thestream.

Referring first to Fig. 1 of the drawings, A is the cable in course ofconstruction, and it will be understood that, by instrumentalities notshown, it is, when the machinery is in operation, progressing axially,in the-direction indicated by the arrow. The tapereel is indicated at 1;it has planetary motion around the advancing cable; its axis ,,isinclined as shown, and from it the-cable as it advances draws the tape aand lays it down about itself in the helical wrap indi- 'cated.

The planetary motion spoken of is imparted to the reel 1 by .mountingiton an arm 2, carried on a hub 3 rotatable in a bearing concentric withthe cable, and by providing rotating means, such. as indicated in thepinion 4, for example.

for this hub conveniently takes the form of the journal box 5, and thehub is conveniently of-annular form, to permit the passage of the cablecentrally through it.

Integral with hub 3(is a casing 6 arranged, when the parts are assembledas shown in Fig. 1, to surround, and to form a substantially closed cellor chamber 7 about the cable, at the point in itspadvance where the tapeis progressively laid upon its surface. Openings for the free advance ofthe cable The bearingand for the feeding in of the tape are sufficientlyindicated in Fig. l. The journal box 5 is chambered, and the chamber 8within it is constantly in communication with the chamber formed bycasing 6. A duct 9 leads to the chamber 8, and through it, it will beunderstood, liquid insulating compound at proper temperature may be sup-.plied, and there needs only suitable head or pressure upon this liquidsupply to keep the chamber 7 filled constantly with compound.

communication with chamber 8, and to that Under these conditions thevery point where the tape comes to place upon the cable isv constantlysubmerged in compound, and thus the danger of pocketing air at thatpoint is avoided. We have said that the cell or chamber 7 issubstantially closed. It will be understood that the cable in the courseof building must as it passes into and out of the chamber 7 move withs'ufiicient clearance through the orifices .formed for its passage, andthat similarly the tape enter-- mg the chamber must also have sufiicientclearance to permit of its ready advance to the point of application.These conditions being understood, it will follow that liquid insulatingcompound will during the operation be escaping in relatively smallquantities through the openings provided for the entrance and the exitof the cable parts to and from the chamber 7 which overflow may bysuitably provided means he collected beneath.. It will thus be apparentthat during the operation there is a continual flow of insulatingcompound throu h the duct 9 and into chamber-7, a part 05 the compoundso entering chamber 7-. enteringinto the composition of the cable andpart escaping again as overflow. I

The modification shown in Fig. II is easily understandable. Asbeforethere is the tape reel 1, borne by an arm 2, upon a hub 3, with meansfor rotation, such as a pinion t. There is a journal box 5 within whichthe hub turns. As before, the hub is annular, to permit the advanceofthe cable A. The journal box is chambered, as indicated at 8, and aliquid supply duct communicates with that chamber. c Instead of theenveloping casin 6 of Fig. 1, the hub is in this case provi ed with aliquid chamber 7 arranged to be always in end-annular; and from chamber7 extends a nozzle 10, directed beneath the advancing tape a, and to thevery point where the'tape comes tomposition upon the surface of thecable. Thus it will be understood that the same-essential end isattained as is attained by the apparatus of Fig. I.the very point wheretape meets the surface of the cable is always flushedwith compound, tothe prevention of air pockets or bubbles. It will of course beunderstood the proportions are such and the head of liquid issufficient, to

, stood.

herein .we have indicated that our invention permits of latitude inembodiment; and it will be understood further that the structure may bemodified in detail, so long as the essential features which we are aboutto define are retained.

In the foregoing description the wrappedon material mentioned is paper,and the building up of the insulation'includes a soaking up of liquid,into the pores of the paper. As is well known to cable makers, laminateinsulation may be built up of material other than paper-varnished cloth,for instance. This is a material which is not absorbent, and if such awrapping material be used, then the insulating compound merely fillsinterstices and seals and integrates the whole...

The compound is of such nature that it may be applied in liquid form.Ordinarily it is such that at,atmospheric temperature it is nearlysolid--as nearly solid as it may be, while the'cable retains. therequisite flexibility. In such case the cable-building operationdescribed above is carried out at elevated temperature, a. temperatureat which the compound is liquid. But of course a compound which isliquid at atmospheric temperature (and for certain ends compound of suchcharacter is used) does not require of the operation that it beperformed at elevated temperature. Again, a liquid may be employed whosefluidity is due to the presence of a volatile ingredient, whichevaporating will leave the structure firm and coherent.

In building a condenser there is no central body, and the interiorconductor is ordinarily not rigid and self-sustaining; accordingly, acentral mandrel will ordinarily be employed. In this case too there willordinarily be little or no advance of the mandrel in axial direction aswrapping progresses; the'wrapped-on material maybe in sheet form,rather-than in ribbon form, and the wrapping'may be truly spiral. Withthese comments, the applicability of our invention to condenser makingwill be under- It is not in the electrical field only that suchstructures are useful; instance the paper cartridges used in shot guns,mailing tubes made of'paper, conduits for various purposes, In makmgthese articles and articles for other uses consisting ofa laminatestructure integrated with a substance which at the time of building isliquid, our invention is manifestly applicable.

\Ve claim as our invention:

1. Apparatus for winding a strip of material into helical form includinga hub rotilting on a bearing, an arm borne by said hub, a reel carriedon said arm and adapted to carry the strip to be wound, chambers in saidhub and in said bearing in constant comunication one with the other, andmeans for maintaining through said chambers a constant supply of liquidat the pointof application of a strip unwound from said' reel and coiledupon a forming article advancing in the line of axis of said hub,substantially as described.

2. In a machine for integrating sheet material and liquid material inlaminate structure upon a forming body, the combination of a tape-reelhaving planetary motion about a path of axial travel of a forming body,a hub upon which said reel is carried, a bearing forsaid hub. chambersin said hub and said bearing constantly in communication one withanother, a fluid-supply duct leading to the chamber in the bearing, thechamber in the hub shaped and arranged to envelop the point where thetape comes progressively to shape upon the forming body, substantiallyas described.

3. In a machine for building laminate cylindrical bodies of insulation,the combination of a tape-reel having planetary motion around a path ofaxial travel of a cylindrical body, a hub upon which said reel iscarried, a bearing for said hub, chambers in said hub and in saidbearing in constant communication one with another, a fluid supp lyductleading to the chamber in said bearingand means for maintaining throughsaid chambers a constant supply of liquid at the point of application ofa strip unwound from said reel and coiled upon a cylindrical bodyadvancing in said path of axial travel, substantially as described.

4. Apparatus for integrating sheet material and liquid material upon aforming body, including a reel for the sheet material having planetarymotion about the forming body, and means for causing the liquid materialflowing in a stream constantly to submerge the sheet material and theforming body at the point where the sheet material meets the surface ofthe forming body, substantially as described. a

In testimony whereof we have hereunto set our hands. 7

CHARLES V. DAVIS. VVI'LLIAM S. BROWN. lVitnesses JOHN W. SHIBLER, HARRYG. BURD.

